Reland of Untouch out of bound pixels for CopyTexSubImage2D

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 5bf0492c8d49a6650c21b06423fe6c87ad236e7a..d8571ebe1a1124effd65900490c0abe61e8df540 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -11393,6 +11393,10 @@ void GLES2DecoderImpl::DoCopyTexSubImage2D(
   Clip(x, width, size.width(), &copyX, &copyWidth);
   Clip(y, height, size.height(), &copyY, &copyHeight);
 
+  xoffset += (copyX - x);

[Zhenyao Mo, 2016/01/20 00:26:49]

What I mean is, do not modify xoffset, yoffset, width, and height here.

Declare destX, destY here, and in the CombineAdjacentRects(), use destX, destY,
copyWidth, copyHeight instead of xoffset, yoffset, width, height.

[qiankun, 2016/01/20 01:02:50]

Done.

+  yoffset += (copyY - y);
+  width = copyWidth;
+  height = copyHeight;
   if (xoffset != 0 || yoffset != 0 || width != size.width() ||
       height != size.height()) {
     gfx::Rect cleared_rect;
@@ -11417,31 +11421,9 @@ void GLES2DecoderImpl::DoCopyTexSubImage2D(
     texture_manager()->SetLevelCleared(texture_ref, target, level, true);
   }
 
-  if (copyX != x ||
-      copyY != y ||
-      copyWidth != width ||
-      copyHeight != height) {
-    // some part was clipped so clear the sub rect.
-    uint32_t pixels_size = 0;
-    if (!GLES2Util::ComputeImageDataSizes(
-        width, height, 1, format, type, state_.unpack_alignment, &pixels_size,
-        NULL, NULL)) {
-      LOCAL_SET_GL_ERROR(
-          GL_INVALID_VALUE, "glCopyTexSubImage2D", "dimensions too large");
-      return;
-    }
-    scoped_ptr<char[]> zero(new char[pixels_size]);
-    memset(zero.get(), 0, pixels_size);
-    glTexSubImage2D(
-        target, level, xoffset, yoffset, width, height,
-        format, type, zero.get());
-  }
-
   if (copyHeight > 0 && copyWidth > 0) {
-    GLint dx = copyX - x;
-    GLint dy = copyY - y;
-    GLint destX = xoffset + dx;
-    GLint destY = yoffset + dy;
+    GLint destX = xoffset;
+    GLint destY = yoffset;
     glCopyTexSubImage2D(target, level,
                         destX, destY, copyX, copyY,
                         copyWidth, copyHeight);